In the production of plywood, chipboard, paneling, and the like a press is used having a pair of main outer platens between which can be sandwiched a plurality of panel workpieces alternating with intermediate platens. A plurality of heavy-duty hydraulic cylinders press one of the outer platens toward the other while the workpieces and intermediate platens are heated to compress and cure the workpieces.
U.S. Pat. No. 5,634,398 describe such a platen press with the actuating cylinders provided underneath the lower platen, the upper platen being fixed. Such an arrangement eliminates the need for double-acting cylinders since the weight of the press can serve to open it. Here there are separate low- and intermediate-pressure accumulators connected in a complex arrangement to different groups of the actuating cylinders.
The main problem with this arrangement is that it is very complex. Furthermore considerable of the nitrogen used as the head above the fluid in the accumulators is lost, in particular from the low-pressure accumulator as gas dissolved in the fluid devolves out as the pressure drops.